Reaction Kinetics and Degradation Pathway of Tetracycline in Ozonation

Tetracyclines are the second most common antibiotic group, in both production and usage, worldwide. Conventional drinking water treatment processes were not designed to remove trace quantities of chemicals such as antibiotics and, given the increasing number of reports of their presence in the environment, it is essential that alternative technologies be developed which effectively degrade or remove these compounds. Ozonation of Tetracycline (TC) in aqueous media was performed at pH 2.2 and 7.0 to find the effects of protonation and variation in free radicals exposure on the reaction mechanism. Ozonation was found to be an effective process degrading TC completely within 4-6 min of ozonation, with overall 1st order kinetics. Ozonation products could be detected and a pattern of their production and subsequent degradation could be established. Pathway of TC degradation during ozonation at pH 2.2 could be proposed based on TC structure, ozonation chemistry and MS data. During this process total organic carbon removal could reach a maximum of ˜40% even with the use of heterogeneous catalyst. This low efficiency might be due to high TC concentration and low ozone supply. Ozonation decreased the toxicity of TC faster at pH 7.0 but the maximum decrease was ˜40% in both cases when ozonation was prolonged for 2 hrs. Overall, ozonation was found to be a promising process to remove TC and its first generation